If the pre-filter isn't catching the cat hair then it isn't doing its job. If it is a non-woven fiber media you might try replacing it with a cheap pleated filter. Fiber pre-filters are really only good for lint.
My parents had an electronic filter installed to reduce dust. The installers removed the main filter which resulted in even more dust - and cat hair - blowing through the system. I installed a large (24 X 30) filter box at the return air grill and the problem went away.
Just don't make the mistake of getting a high dollar MERV-12 filter thinking it will be even better. Fine filtration elements cause excessive pressure drop unless you substantially increase the total filter area. The first 24 X 30 filter I installed had so much pressure drop it collapsed the return duct. And this was only a 2 ton unit.
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